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Abstract

Background

Cross-country differences in dietary behaviours and obesity rates have been previously
reported. Consumption of energy-dense snack foods and soft drinks are implicated as
contributing to weight gain, however little is known about how the availability of
these items within supermarkets varies internationally. This study assessed variations
in the display of snack foods and soft drinks within a sample of supermarkets across
eight countries.

Methods

Within-store audits were used to evaluate and compare the availability of potato chips
(crisps), chocolate, confectionery and soft drinks. Displays measured included shelf
length and the proportion of checkouts and end-of-aisle displays containing these
products. Audits were conducted in a convenience sample of 170 supermarkets across
eight developed nations (Australia, Canada, Denmark, Netherlands, New Zealand, Sweden,
United Kingdom (UK), and United States of America (US)).

Results

The mean total aisle length of snack foods (adjusted for store size) was greatest
in supermarkets from the UK (56.4 m) and lowest in New Zealand (21.7 m). When assessed
by individual item, the greatest aisle length devoted to chips, chocolate and confectionery
was found in UK supermarkets while the greatest aisle length dedicated to soft drinks
was in Australian supermarkets. Only stores from the Netherlands (41%) had less than
70% of checkouts featuring displays of snack foods or soft drinks.

Conclusion

Whilst between-country variations were observed, overall results indicate high levels
of snack food and soft drinks displays within supermarkets across the eight countries.
Exposure to snack foods is largely unavoidable within supermarkets, increasing the
likelihood of purchases and particularly those made impulsively.

Keywords:

Snack foods; Food environment; Supermarket; International comparison

Background

There has been a continued growth in global obesity rates over recent decades although
the trajectory of these increases has varied across developed nations [1,2]. The higher prevalence of obesity has put large numbers of individuals at increased
risk of type 2 diabetes, cardiovascular diseases and some cancers [3-5].

Snacking behaviours have increased in parallel with obesity prevalence [6-8]. Evidence has linked the increased consumption of energy-dense snack foods with greater
waist circumference in adults [9] while sugar-sweetened beverage consumption (e.g. soft drinks) is increasingly implicated
in the development of obesity [10]. Although existing studies allow us to assess snack food consumption in individual
countries [7,11-19], international comparison studies remain relatively rare. Those studies including
data from multiple countries consistently report large differences in purchasing and/or
consumption across countries [20-25].

Environmental factors including opportunities to purchase and consume food are increasingly
seen as an important determinant of dietary behaviours [26]. Within food stores, consumers are faced with variations in the quantity, quality,
price and marketing of food items [27-30]. Supermarkets are a major source of food for many households as they are usually
highly accessible (both in terms of location and opening hours) and enjoy market domination
in food/grocery retail expenditure in many developed nations (including Australia
[31,32], Canada [33], Sweden [32], the US [34], and the UK [35]). As a setting for within-store food availability research, supermarkets are therefore
an important priority.

Supermarket retailers have long known that the placement and marketing of products
is a key determinant of purchasing decisions with marketing tactics being particularly
important for sales of impulse items in comparison with staples [30,36-40]. Market research findings have demonstrated that almost two thirds of in-store food
purchasing decisions are unplanned, [41] highlighting the potential for purchasing and consumption to be influenced by within-store
displays and particularly those in highly visible areas (e.g. at end-of-aisles and
checkouts). Our previous assessments of the supermarket snack food environment (from
Melbourne, Australia) showed snack foods to be almost ubiquitous at supermarket checkouts,
and extremely common in end-of-aisle displays and temporary island bins [42]. A significant amount of supermarket shelf space was also dedicated to snack foods
and soft drinks as static displays in aisles [43]. The few other studies of supermarket snack foods conducted to date have been restricted
to individual cities [44-48] with the exception of Farley et al. who conducted one study across 19 US cities [49] and another across two US cities [50]). These two US studies also concluded that snack foods were readily available within
a range of retail food store types [49,50]. All previous studies have limited comparability because of the use of an assortment
of measurement techniques and no international comparisons have been previously published.

In the present paper we use data gathered in a standardized manner from supermarkets
in eight different countries to examine the availability of snack food (potato chips,
chocolate, and confectionery) and soft drinks in the shelves, at checkouts and in
end-of-aisle displays. Shelf space of fruit and vegetables were also assessed for
comparative purposes. Our focus on energy-dense snack foods and soft drinks was based
on the above mentioned established links between consumption of such products and
health and the fact that consumption of such products is common across the eight developed
countries. International comparison studies of the within-store food environment such
as this are an important way of placing local findings into a global context and can
provide significant insights for policy and advocacy toward healthier food environments.

Methods

Sampling

A total of 170 supermarkets were audited across selected cities in eight developed
countries (Table 1) using a standardized audit tool (Additional file 1: Appendix A). The study involved an international collaboration with data collection
in each country organised by the local research team. Many of the auditors had face-to-face
contact with the lead investigators (LET & AJC) prior to the collection of data and
each auditor was provided with the audit tool and a detailed instruction manual (including
photographic instructions) (Additional file 1: Appendix A). A more expansive audit tool was used for the data collection in Australia,
Canada (Montreal only), Denmark, and the Netherlands but some measures were removed
(e.g. variety, price, island bin displays) for the remaining countries to reduce auditor
burden and to keep only those features that were readily comparable between countries.
Auditors contacted the lead investigators with any questions that arose during data
collection.

Table 1.Sample characteristics of the 170 included supermarkets from 8 countries

Additional file 1.Appendix A. Supermarket snack food audit tool. *Please note the audit tool is freely available
for other researchers to use (instruction manual also freely available on request
to the corresponding author). Please acknowledge the audit tool developers when reporting
findings based on the use of this audit tool.

The data collection for Australia took place between September 2010 and February 2011
whilst the audits for the other countries were conducted between May 2011 and July
2012. In Australia [43], Denmark, the Netherlands and Canada (Montreal only) supermarkets were sampled from
neighbourhoods within the least and most socioeconomically disadvantaged areas. While
auditors were instructed to sample from a representative range of areas, no explicit
sampling criteria were followed and auditors sampled from their cities of residence
or other region convenient to them. Therefore, the actual areas sampled should be
considered a convenience sample.

The local supermarket retailers from each region were included in the audits. In some
countries this meant only a limited number of chains were sampled whereas elsewhere
multiple chains were sampled as this reflected the increased diversity with the local
supermarket industry.

The project proposal for data collection in Melbourne was assessed by a Human Research
Ethics Advisor from the Office of Research Integrity at Deakin University who advised
that ethics committee approval for the study was unnecessary because data collection
did not involve personal disclosure. Ethical assessment was the responsibility of
each collaborator where it was required by their host institutions. In each instance
ethics approval was not required as this research did not involve human participants.
Auditors gained consent from store managers prior to taking any measurements within
a store.

Data collection

Items included

A universal definition of “snack food” does not exist [51,52], and for the purpose of this research we restricted our definition to food and beverage
types that are often consumed outside of the three main meals and would be considered
high in energy, high in sodium, and/or low in micronutrients. These items included
potato chips (crisps) (includes corn chips but not savoury crackers or pretzels),
chocolate (either as chocolate bars, blocks, boxes or bags), confectionery (candy)
(excluding mints and chewing gum) and soft drinks (soda) (both diet and regular).
Each of these product types were easily identified in distinct sections in most supermarkets,
readily available in the eight included countries, and form part of a typical Western-style
eating pattern. Both diet and regular soft drinks were included because they are often
interspersed within the same shelves (i.e. not stocked in separate sections) preventing
us from taking separate aisle length measures for these two products. Fruit and vegetable
availability was also measured (fresh products only, not tinned, dried or frozen)
to allow an assessment of the ratio of snack foods to fruits and vegetables within
stores.

Shelf space

The total aisle length (in metres) dedicated to each of the four snack food and beverage
groups (i.e. potato chips, chocolate, confectionery and soft drinks) was measured
using a measuring wheel or measuring tape. This involved measuring from the point
in the aisle where the snack food category began to where the display of that category
ended. In the stores from the Bethesda/Washington DC area, a measuring device was
not available and instead the length was determined by calibrated length of paces.
If an item (e.g. confectionery) was displayed in multiple aisles, the total length
across the multiple aisles was summed. For fruits and vegetables, the length of shelf
space (refrigerated and un-refrigerated) as well as the circumference of island displays
dedicated to fresh fruits and vegetables were measured and summed.

Checkouts and end-of-aisle displays

Auditors assessed whether snack foods were available at each checkout and at end-of-aisle
displays at both the front and the back of an aisle. Using a checklist, the presence
of each of the following items was recorded: 1) potato chips; 2) chocolate; 3) confectionery;
4) soft drink – regular; 5) soft drink –diet. Multiple item types could be recorded
for each checkout or end-of-aisle display.

Store size

Total store size was calculated as total length of all aisles in the supermarket measured
using a measuring wheel, measuring tape, or calibrated paces.

Analysis

The estimated marginal mean of the total aisle length of snack food items and the
aisle length of individual snack food items was calculated adjusting for total store
size across all countries. The ratio of aisle length dedicated to snack foods compared
to fruits and vegetables was calculated by dividing the total aisle length of snack
foods by the total length of displays of fruits and vegetables. Shelf length of each
product type and the ratio of snack food to fruits and vegetables for each country
were ranked from the most (1) to the least (8). The proportion of total snack food
aisle length dedicated to each of the snack food and soft drink items was calculated
for each store to produce a within-country mean. This measure allowed us to assess
the relative amount of each item within countries. For checkouts and end-of-aisle
displays, results are reported as a percentage (and 95% confidence interval) of the
total number of checkouts or end-of-aisle displays that displayed any snack food item.

Results

Included data originated from Oceania, North America and Europe. In Oceania, in addition
to a sample of 35 supermarkets from Melbourne, Australia on which we have previously
reported [42,43], data was also obtained from 10 supermarkets in Wellington (New Zealand). A sample
of 60 North American supermarkets were obtained from two cities in Canada (Montreal
(n = 18) and Toronto (n = 10)) and three cities in the United States (US) (Columbia,
SC (n = 14); Philadelphia, PA (n = 9); and Bethesda, MD/Washington DC (n = 9)). In
Europe, audits were conducted in Copenhagen and surrounding urban areas (Denmark,
n = 18), Amsterdam (the Netherlands, n = 20), Stockholm (Sweden, n = 19) and Oxford
(United Kingdom (UK), n = 8) (Table 1).

Shelf space

Aisle length dedicated to each snack food type is presented in Table 2 in addition to the country ranking for each item relative to other countries. Large
variations for each snack food type as well as the total aisle length of snack food
were observed between countries. Adjusted for total store size, supermarkets in the
UK sample had the greatest aisle length dedicated to chips, chocolate and confectionery
as well as the greatest total snack food aisle length (56.4 m; 95% CI 47.6 – 65.2
m). Aisle length of soft drinks was greatest in the Australian sample (18.4 m; 95%
CI 16.6 – 20.3 m). Stores in the New Zealand sample had the least aisle length dedicated
to snack foods (21.7 m; 95% CI 13.8 – 29.7). Raw aisle length (unadjusted for store
size) values for each country are found in Additional file 2: Appendix B. Stores in the Danish and the UK samples had the highest ratio of snack
foods to fruit and vegetables with a ratio of 1.46 and 1.31 respectively (Table 2). The Canadian supermarkets had the lowest ratio of snack food aisle length to fruits
and vegetables aisle length.

Table 2.Shelf space (aisle length in metres) dedicated to energy-dense snack foods and drinks
(adjusted for total store size) and ratio of snack food to fruits and vegetables and
between-country rankings for each item

The proportion of the total snack food aisle length dedicated to each type of snack
food is presented in Figure 1. Supermarkets in the North American countries (Canada and the US) had a greater proportion
of their snack food aisle length dedicated to chips. Compared to other countries,
the UK sample had a higher proportion of total snack food shelf length allocated to
chocolate while the greatest proportion of shelf length allocated to confectionery
was found within the Swedish sample. Soft drinks were less prominent as a proportion
of total snack food aisle length in the Swedish and UK supermarkets.

Checkouts and end-of-aisle displays

The only sample of supermarkets in which less than half of all checkout displays featured
any of the snack foods or soft drinks assessed were those in the Netherlands (41%)
(Figure 2). In every other country, our samples of supermarkets had more than 70% of checkouts
featuring snack foods or soft drinks, with the mean percentage being highest in Australia
(99%). The total number of checkouts in the UK sample was not recorded and therefore
we could not calculate the proportion of checkouts with snack foods within that country.
The percentage of checkout displays in each country featuring each of the individual
product types is presented in Additional file 2: Appendix C. Of particular interest in this appendix is the diversity of snack foods
available at the checkouts with the US sample compared to countries such as Australia
where checkouts largely display chocolate or soft drinks.

Australian supermarkets also exhibited the highest percentage (39%) of end-of-aisle
displays featuring snack foods or soft drinks, with the proportion from the samples
in other countries ranging from 16% (New Zealand) to 30% (Canada) (Figure 2). Additional file 2: Appendix D contains the percentage of end-of-aisle displays in each country featuring
each of the individual product types.

Discussion

This study investigated the exposure to energy-dense snack foods (chips, chocolates
and confectionery) and soft drinks in a sample of supermarkets across selected cities
in eight developed countries. The shelf length of snack foods and the presence of
these foods at checkouts and in end-of-aisle displays were assessed with noticeable
variations detected between countries. UK supermarkets had the greatest aisle length
devoted to chips, chocolate and confectionery, while soft drink aisle length was greatest
in Australia. The proportion of both checkouts and end-of-aisle displays containing
snack food was also highest in the Australian supermarkets sampled. In every country
other than the Netherlands, snack foods were present at over 70% of checkouts.

From the results of this cross-sectional study, we are not able to discern whether
variation is a result of differences in demand between countries, or whether supply
is driving demand. It is likely that both are contributing. Demand may be driven strongly
by cultural norms and traditional diet preferences. Influences on the supply side
of the equation may include specific commercial arrangements between retailers and
the food industry/suppliers, climatic differences between countries that influence
the availability and price of supermarket items, agricultural policies such as the
subsidisation of high-fructose corn-syrup production (for use as a sweetener in soft
drinks) by the US government [53], import tariffs and trade agreements. The position of supermarkets in the larger
food shopping environment may also explain some of the variation observed here. For
example, it is likely the role of supermarkets in supplying fresh fruit and vegetables
to consumers varies between nations based on the prominence and use of other retailers
such as greengrocers or markets. Such variations may have contributed to the differences
in the ratio of snack foods to fruits and vegetables that we observed.

Some of the findings reported here can be compared with the results of previous studies
from individual countries. A 2006 study from Melbourne, Australia reported that 99%
of checkouts displayed snack foods or soft drinks [45] which is consistent with our own findings from that city. Prior US research [46,50] using a more inclusive definition of snack foods (included such items as nuts, cookies,
doughnuts) found greater shelf lengths dedicated to snack food items than we report
here. Because of the differences in definitions, the results from this study and our
own study are not directly comparable.

Whilst the broader dietary and health implications of supermarkets have been discussed
elsewhere [29,30], the link between snack food availability and both purchasing behaviour and health
indicators warrants consideration. Although research in this area is in its infancy,
a couple of studies have been published. One prior Australian study did not find any
link between snack food shelf length and purchasing [54]; however that study of only nine supermarkets was underpowered to detect a significant
effect. In the US, a positive correlation between snack food shelf space and BMI was
observed [55] however the effect size was small. Many policy and program interventions are already
aiming to change food environments even though robust and consistent evidence is not
yet available and a consensus on how change should best be achieved has not yet been
reached [27]. Additional studies linking within-store environments with purchasing habits, diets
and obesity are therefore sorely required to support the obvious desire to improve
our food environment.

While ecological data of the type reported from this study cannot infer causality,
links between availability and national consumption patterns are of interest. In Dutch
supermarkets, greater shelf space was allocated to soft drinks in comparison with
the other snack foods assessed. This result correlates with the findings from the
ENERGY study (which examines health in children across seven European countries) in
which extremely high soft drink consumption amongst Dutch children was reported [20]. Furthermore, soft drink consumption in the Netherlands has increased by 74% between
1980 and 2009 [56]. In the North American supermarkets audited, shelf space devoted to soft drinks and
potato chips was greater than for confectionery and chocolate in comparison with the
other countries assessed. Within the US, soft drinks (soda) were reported to be the
top dietary source of added sugars [57,58] whilst potato chips were the top dietary source of oils [58]. Amongst U.S. children both soft drinks and potato chips make substantial contributions
to overall energy intake [57]. The Swedish population has traditionally had a preference for sugar confectionery
[59]. Of interest however, are changes between 1980 and 2010 in the consumption of different
snack foods and drinks. In that period, chocolate and confectionery (combined) increased
by 53% per capita in Sweden whilst the consumption of soft drinks (including flavoured
carbonated water) over this period increased three-fold and consumption of potato
chips increased four-fold [60]. These changes in consumption are reflected in the current snack food profile in
Swedish supermarkets in which shelf space of confectionery and chocolate is no higher
than for chips and soft drinks (noting that our measure does not include carbonated
water). Although it is of interest to examine correlations between availability and
consumption patterns, the lack of comparable national dietary indicators limits our
ability to explore this in more detail.

Whilst limiting snack food exposure in other settings such as schools and workplaces
has been a focus of some public health campaigns [61,62], the supermarket environment is increasingly recognised as a potential intervention
point [29]. In addition to facilitating comparisons between countries, the results of this study
also allow the assessment of the local food environment in each country. Such national
food environment data is necessary to support and justify campaigns such as those
calling for the removal of confectionery items from supermarket checkouts [61,63,64]. Efforts to improve diet and reduce obesity and other chronic diseases will be more
successful when supported by strategies such as these that aim to create healthier
environments. In the Netherlands, the Albert Heijn supermarket chain has the largest
market share (34%) [65] and remains a profitable supermarket retailer despite not having high levels of snack
food displays (relative to other supermarkets in this study). In reaction to a report
by the Dutch Consumers’ Federation [66] on which supermarkets make the healthy choice the easy choice, Albert Heijn announced
an initiative to remove all snack foods from checkouts. This action is reflected in
the low proportion of Dutch checkouts with snack food displays observed in this study.
That example suggests that such initiatives may involve a relatively low cost for
supermarkets, can allow them to promote their brand as a healthy choice, and may be
important in changing cultural norms around snacking behaviours. Other forms of advocacy
to encourage healthier supermarkets are required [29] and these may include policy-level approaches initiated by governments.

The major strength of this study is the within-store assessment of energy-dense snack
foods and soft drinks conducted in a sample of supermarkets across cities in multiple
countries using a standardized measurement tool. Multiple aspects of the within-store
food environment were captured, including static displays of shelf space and dynamic
displays at ends-of-aisles and checkouts. Previously, within-store assessments of
supermarket snack foods have been rare, limited in their ability to compare findings
between countries and did not include the multiple aspects of the supermarket snack
food environment assessed here.

We acknowledge that our definition of snack food was limited to four food categories.
Other types of energy-dense snack foods not captured here are also available in supermarkets
and in certain contexts these products may also be important snack foods (e.g. cookies
and ice-cream in North America). While no universal definition of snack foods exists
[51,52], the definition used in this study was appropriate for a cross-country comparison
as each of the snack foods examined were commonly available in all countries. The
sampling strategy should also be considered when interpreting the findings. In Melbourne,
Amsterdam and Montreal, data collection was undertaken according to area level disadvantage.
Auditors in other countries sampled from a representative range of urban areas with
no pre-specified stratification according to area-level disadvantage. All collaborators
were instructed to sample from the major supermarket retailers in their setting. Although
this meant that a greater variety of chains were sampled in some countries than others,
we would expect that the diversity of store types in a country is a valid reflection
of the choices available to consumers. The fourth limitation relates to the relatively
small number of supermarkets examined in two of the countries (New Zealand and the
United Kingdom). The findings from these two countries in particular should be treated
with some caution as they may not accurately represent snack food availability in
those settings. Despite adjusting for store size in our analysis, we did not have
any indicator of the presence of non-food items present and it is possible that in
some larger stores, a greater proportion of the store was allocated to such products.
We did, however include an assessment of the ratio of snack foods to fruits and vegetables
which is an effective indicator of the priority given to snack food relative to other
items. Finally, other factors that may be important determinants of snack food purchasing
(e.g. price, in-store promotions, variety, island bin displays) were not included
in this study because of difficulties in comparing such features between countries.

Conclusion

Globally, supermarkets play an increasingly important role in shaping dietary behaviours.
This study has highlighted the ubiquitous presence of energy-dense snack food items
in the supermarkets of eight developed countries. Although differences were observed
between countries, snack food was extremely common in the aisles of supermarkets in
all countries. The prominence of snack foods in displays at checkouts and the ends-of-aisles
may be an important determinant of snack purchases as such displays are largely unavoidable.
The relatively low prominence of snack food in supermarkets in both the Netherlands
(checkouts in particular) and New Zealand suggest that lessons about the reduction
of such displays may be learnt from these countries.

Competing interests

The authors declare that they have no competing interests.

Authors’ contributions

LET and AJC designed the audit tool with the assistance of SAM. LET and AJC oversaw
the data collection within Melbourne and analysed the data for the entire sample.
All other listed authors either coordinated or conducted the data collection within
their country. LET and AJC wrote the first draft of the paper with the assistance
of SAM and DAC. All authors assisted in drafting the manuscript with each author providing
context-specific contributions. LET had primary responsibility for the final content.
All authors read and approved the final manuscript.

Acknowledgements

We would like to acknowledge the contribution of the following people who assisted
with this study: Jennifer McCann, Kate Udorovic, Leah Salmon, Alexander Hamilton,
Jessica Chen, Anna Schöni, Xiaoguang (Max) Ma, Jindong Ding Petersen, Nishan Lamichhane,
Jesper Friberg (within-store audits) and Brian Miller for his assistance with the
development of the database used to enter and manage the audit data.

The collection of data within Melbourne was supported by funding through Deakin University.
LET is supported by a Deakin University Alfred Deakin Postdoctoral Research Fellowship.
AJC is supported by a National Health and Medical Research Council Fellowship (#1013313).
SAM is supported by an Australian Research Council Future Fellowship (FT100100581).
CF is funded by the British Heart Foundation. CS is supported by The Nordea Foundation.